Edicaran post-collisional volcanism in the Arabian-Nubian Shield: The high-K calc-alkaline Dokhan Volcanics of Gabal Samr El-Qaa (592±5Ma), North Eastern Desert, Egypt

Lu–Hf and O isotopic compositions on single zircons from the North Eastern Desert of Egypt, Arabian–Nubian Shield: Implications for crustal evolution

“…U-Pb zircon ages of 630-590 Ma were reported for the Dokhan Volcanics (Wilde and Youssef, 2000;Breitkreuz et al, 2010), thus the A-type granite (younger granites) perhaps was part of NED bimodal activity (Eliwa et al, 2014). In summary, it is likely that the mantle-derived magma which produced the Dokhan Volcanics evolved to rhyodacite-rhyolite and their subvolcanic equivalents (Breitkreuz et al, 2010;Eliwa et al, 2014). Fractional crystallization of the Dokhan mafic magma at the crust boundary perhaps acted as a crustal heat source and triggered partial melting of the middle to lower crust to produce the~600 Ma A-type magmas (e.g., Wang et al, 2014).…”

“…Overall, the sources of the four granitic plutons we studied are remarkably similar isotopically, in spite of larger differences in chemical composition. Field investigation indicated that post-collisional stage~600 Ma was characterized by the eruption of calc-alkaline volcanic rocks (Dokhan Volcanics) and felsic intrusions (younger granites) in the NED (Moghazi, 2003;Breitkreuz et al, 2010;Eyal et al, 2010;Eliwa et al, 2014). U-Pb zircon ages of 630-590 Ma were reported for the Dokhan Volcanics (Wilde and Youssef, 2000;Breitkreuz et al, 2010), thus the A-type granite (younger granites) perhaps was part of NED bimodal activity (Eliwa et al, 2014).…”

“…Field investigation indicated that post-collisional stage~600 Ma was characterized by the eruption of calc-alkaline volcanic rocks (Dokhan Volcanics) and felsic intrusions (younger granites) in the NED (Moghazi, 2003;Breitkreuz et al, 2010;Eyal et al, 2010;Eliwa et al, 2014). U-Pb zircon ages of 630-590 Ma were reported for the Dokhan Volcanics (Wilde and Youssef, 2000;Breitkreuz et al, 2010), thus the A-type granite (younger granites) perhaps was part of NED bimodal activity (Eliwa et al, 2014). In summary, it is likely that the mantle-derived magma which produced the Dokhan Volcanics evolved to rhyodacite-rhyolite and their subvolcanic equivalents (Breitkreuz et al, 2010;Eliwa et al, 2014).…”

“…ANS rocks are exposed on both sides of the Red Sea due to continental rifting and rift shoulder uplift at~30 Ma (e.g., Reymer and Schubert, 1984;Dixon and Golombek, 1988;Stern, 2002;Stein, 2003;Hargrove et al, 2006). The evolution of the ANS during the time interval 810-740 Ma was accomplished by formation of juvenile (mantle-derived) crust at intra-oceanic convergent plate margins, followed by collisional welding and intracrustal fractionation of arc systems to form larger tracts of increasingly differentiated continental crust (Stern, 1994;Stern and Abdelsalam, 1998;Ali et al, 2009;Eliwa et al, 2014;Robinson et al, 2014). The tectonic evolution of the ANS is commonly divided into three major stages: 1) Cryogenian collision and subduction (~870-635 Ma) characterized by the development of island arc volcano-sedimentary sequences and I-type plutonic rock; 2) Early Ediacaran continental collision (~630-580 Ma, Bentor, 1985;Avigad and Gvirtzman, 2009;Be'eri-Shlevin et al, 2009b;Johnson et al, 2011) by continuing convergence between East and West Gondwana to form the East African orogen (Stern, 1994), and 3) Late Ediacaran post-collision stage , characterized by stabilization of the shield followed by regionally extensive peneplanation (Avigad et al, 2005).…”

The South Um Mongul Cu-Mo-Au prospect in the Eastern Desert of Egypt: From a mid-Cryogenian continental arc to Ediacaran post-collisional appinite-high Ba-Sr monzogranite

“…Younger (YMV) Metavolcanics (Mohamed et al, 2000;Eliwa, 2006;Moghazi et al, 2012;Eliwa et al, 2014b). The Dokhan Volcanics are characterized by higher alkalis contents, especially K 2 O than the Cryogenian subduction-related metavolcanic rocks, and thus follows commonly the high-K calc-alkaline series (Fig.…”